An object of the invention is to provide a fuel cell system capable of improving accuracy of water content estimation during a standstill. The invention aims at removal of the polluted air in such a way that the servicing interval is greatly extended by the use of a filter unit having a number of part-filters arranged one after the other and formed of pleated fiber mats, the various mats having different filtering properties. Moreover, the assisting device resides on the network. In order to complete a data transfer process, the system of the present invention authenticates the remote computer, determines its authority to act as a designated local user, and determines whether the remote computer, acting as the designated local user, can perform the actions required for the data transfer. Signal paths are positioned toward a backside of the outer surface.